Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$191.39	7.416%	$205.5835	$205.58	$205.60	$205.60
Purchase #2	$210.42	7.151%	$225.4671	$225.47	$225.45	$225.50
Purchase #3	$20.70	6.806%	$22.1088	$22.11	$22.10	$22.10
Purchase #4	$25.48	13.562%	$28.9356	$28.94	$28.95	$28.90
Purchase #5	$143.82	7.319%	$154.3462	$154.35	$154.35	$154.30
Purchase #6	$139.98	4.692%	$146.5479	$146.55	$146.55	$146.50
Purchase #7	$249.93	12.399%	$280.9188	$280.92	$280.90	$280.90
7 purchase totals =	$981.72		$1,063.9079	$1,063.92	$1,063.90	$1,063.80